Flexible mobility framwork for heterogeneous roaming in next generation wireless networks

ABSTRACT

A system and method for mobility support of a mobile node having a home network in a heterogeneous roaming environment is presented. The method comprises the steps of authenticating the mobile node in a visited network and obtaining an address for the mobile node in the visited network, establishing a security connection between a functional component in the visited network and an agent in the home network, creating a home address for the mobile node, and using the home address to generate a SIP signaling address, a SIP media address, and a non-SIP media address, such that SIP non-media is transmitted using the security connection to the SIP signaling address, SIP media is transmitted using the security connection to the SIP media address, and non-SIP media is transmitted using the security connection to the non-SIP media address.

CROSS REFERENCE TO RELATED APPLICATION

The present invention claims the benefit of U.S. provisional patentapplication 60/876,765 filed Dec. 22, 2006, and of U.S. provisionalpatent application 60/930,412 filed May 16, 2007, the entire contentsand disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to next generation wirelessnetworks, and more specifically to a framework for heterogeneous roamingof mobile nodes in such networks.

BACKGROUND OF THE INVENTION

Ubiquitous roaming support for real-time traffic, such as interactiveVoIP, streaming, and the non-real-time data transfer of FTP and e-mailin an access independent manner, is becoming increasingly important. Forexample, the evolution of the mobility protocols of Mobile IPv4 (MIPv4)and Mobile IPv6 (MIPv6) has made it easier to support ubiquitousroaming. Carriers in the wireless Internet have different mobilitycapabilities, and mobile clients may also have a variety of mobilitycapabilities. For example, some operators or carriers may support mobileassisted mobility protocol, such as MIPv6 and Client Mobile IPv6(CMIPv6), while others may support network assisted mobile protocol,such as Proxy Mobile IPv6 (PMIPv6). In some cases, often the mobileassisted mobility protocols, a mobile node or mobile client may beequipped with a mobility stack, and the mobile node may use anapplication layer mobility protocol in certain situations.

In a typical roaming environment, two domains can belong to two separatecarriers with different mobility support and security and authenticationprocedures. Accordingly, a mobile node in the Next Generation WirelessNetworks may be subjected to roaming that may involve different kinds ofmovement scenarios. These movement types can be confined to home domainor visited domain. When the mobile node is away from home and is in thevisited domain, the mobile node is defined to be in roaming mode. Whenin the roaming mode, the mobile node can move between two sub-networksthat may belong to the same carrier domain, or it can move from onecarrier domain to another carrier domain. Any mobile node in roamingscenario may be subjected to several degrees of heterogeneity, such astypes of mobility being supported in the network elements and in themobile node's stack, the type of application supported in the mobilenode and type of movement both in the local domain or in the visiteddomain that might involve changing bearer manager. Also, while in thevisited domain, avoiding exposure of a subscriber's permanent IP addressin the visited carrier networks is important to maintain security.

Several existing standards bodies are attempting to define the corenetwork architecture for next generation wireless networks. ThirdGeneration Partnership Project (3GPP) defined an IP Multimedia Subsystem(IMS) architecture, and 3GPP2 defined the Multimedia Domain (MMD)architecture. Recently, Advances to IMS (A-IMS) architecture, whichenhances existing IMS and MMD networks, has been proposed to support avariety of services such as Session Initiation Protocol (SIP)-based andnon-SIP-based applications. SIP-based applications are typically set upby SIP and provide services such as VoIP. On the other hand,non-SIP-based applications provide services such as IPTV and FTP withoutusing SIP. Similarly, International Telecommunication UnionTelecommunication Standardization Sector (ITU-T) is working on definingthe Next Generation Network (NGN) under the premises of a GlobalStandards Initiative, i.e. NGN-GSI. All these architectures includeheterogeneous access networks, such as CDMA, WiMAX, and 802.11technologies, and include support for roaming.

At present, however, the inventors know of no flexible framework thatcan support seamless mobility between networks with different mobilitysupport.

The following abbreviations are used throughout.

-   3GPP: Third Generation Partnership Project-   AAA: Authentication, Authorization and Accounting-   AGW: Access GateWays-   AN: Access Network-   AS: Application Servers-   CDMA: Code Division Multiple Access-   CMIPv6: Client Mobile IPv6-   CN: Correspondent Node-   DAD: Duplicate Address Detection-   DHCP: Dynamic Host Configuration Protocol-   FTP: File Transfer Protocol-   GGSN: Gateway GPRS Support Node-   GSM: Global System for Mobile communications-   HA: Home Agent-   hHoA: Home Address of node in home domain-   I-CSCF: Interrogating Call Session Control Function-   IETF: Internet Engineering Task Force-   IMS: IP Multimedia Subsystem-   IMS/MMD—combination of IMS and MMD-   IPTV: Internet Protocol TeleVision-   ITU-T: International Telecommunication Union Telecommunication    Standardization Sector-   LCP: Link Control Protocol-   LMA: Local Mobility Anchor-   LTE: Long Term Evolution-   MAG: Mobile Access Gateway-   MIPv4: Mobile IPv4-   MIPv6: Mobile IPv6-   MMD: Multimedia Domain-   MN: Mobile Node-   NAI: Network Access Identifier-   NGN: Next Generation Network-   NGN-GSI: Next Generation Network-Global Standards Initiative-   PCF: Packet Control Function-   P-CSCF—Proxy Call Session Control Function-   PDSN—Packet Data Serving Node-   PMA: Proxy Mobile Agents-   PMIPv6: Proxy Mobile IPv6-   PPP: Point to Point Protocol-   SAE: System Architecture Evolution-   S-CSCF—Serving Call Session Control Function-   SDP: Session Description Protocol-   SIP: Session Initiation Protocol-   URI: Universal Resource Identifier-   vHoA: Home Address of node in visited domain-   VoIP: Voice over IP-   WiMAX: IEEE 802.16 wireless specification

BRIEF SUMMARY OF THE INVENTION

The present invention advantageously provides a solution to the problemsof mobility management, that is, roaming and service continuity, in nextgeneration wireless networks. This invention benefits different types ofroaming, such as home local, visited local, global mobility andcombinations thereof, as well as Simple IP, CMIPv6 and PMIPv6 mobilityoperation, and also addresses heterogeneity of application, e.g., SIP,non-SIP based, being supported on a mobile node. A combination ofapplication layer, network layer and local mobility protocol can be usedbased on the mobile's movement pattern, the mobile's and the network'smobility capability, and the type of application being supported. Thesolution provides a framework useful for supporting inter-carrierroaming involving global and local mobility between domains and withindomains.

In one embodiment, a system and method for mobility support of a mobilenode having a home network in a heterogeneous roaming environment,includes a method comprising the steps of authenticating the mobile nodein a visited network and obtaining an address for the mobile node in thevisited network, establishing a security connection between a functionalcomponent in the visited network and an agent in the home network,creating a home address for the mobile node, and using the home addressto generate an SIP signaling address, an SIP media address, and anon-SIP media address, such that SIP non-media is transmitted using thesecurity connection to the SIP signaling address, SIP media istransmitted using the security connection to the SIP media address, andnon-SIP media is transmitted using the security connection to thenon-SIP media address.

In another embodiment, the method comprises the steps of authenticatingthe mobile node in a visited network and obtaining an address for themobile node in the visited network, establishing more than one securityconnection between a functional component in the visited network and anagent in the home network, creating a home address for the mobile node,and using the home address to generate a SIP signaling address for SIP,a SIP media address for SIP media, and a non-SIP media address fornon-SIP media, such that SIP signaling is transmitted using one of thesecurity connections to the SIP media address, SIP media is transmittedusing another of the security connections to the SIP media address, andnon-SIP media is transmitted using yet another of the securityconnections to the non-SIP media address.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described in the detailed description thatfollows, by reference to the noted drawings by way of non-limitingillustrative embodiments of the invention, in which like referencenumerals represent similar parts throughout the drawings. As should beunderstood, however, the invention is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1 illustrates generic network architecture for next generationwireless networks;

FIG. 2 illustrates network elements associated with PMIPv6;

FIG. 3 illustrates roaming in one embodiment of the invention;

FIG. 4 illustrates a flow of home local mobility; and

FIG. 5 illustrates a flow of mobility with home and visited domains.

DETAILED DESCRIPTION OF THE INVENTION

An inventive solution to the problem of mobility management in nextgeneration wireless networks is presented. This solution is a frameworkfor supporting inter-carrier roaming involving global and local mobilitybetween domains and within domains. When a mobile node changes itsnetwork point of attachment, traffic is disrupted due to the handoverprocess, which can be mobile-node-controlled or network-controlled.Depending on the type of movement, mobility can be handled at the linklayer, the network layer, or the application layer. Link layer mobilityis access specific, so that it cannot solve the problem of heterogeneityand therefore is not discussed.

In network layer mobility, mobility involves heterogeneous accesstechnologies, and can be controlled either by the mobile node or thenetwork. In a mobile-controlled scenario of network layer mobility, themobile node is usually equipped with a mobility stack and interacts witha remote entity such as a Home Agent (HA). An example ofmobile-node-controlled mobility is CMIPv6. In the network layermobility, when the mobility protocol is network-controlled, othernetworking elements in the middle of the network interact with theremote entity, typically an HA, and perform handoff related functions.

FIG. 1 illustrates the functional components of generic networkarchitecture for next generation wireless networks for providingubiquitous services that need mobility support along with quality ofservice, security and charging. This generic network comprises a homenetwork 10 and a visited network 12, which can also be consideredanother home network. In addition, it includes IP core entities of MN ormobile node 14, access gateways (AGW) 16, home agents (HA) 18, andauthentication, authorization and accounting (AAA) 20. It also hasIMS/MMD entities of Proxy Call Session Control Function (P-CSCF) 22,Interrogating Call Session Control Function (I-CSCF) 24, Serving CallSession Control Function (S-CSCF) 26, home subscriber service (HSS) 28,application server (AS) 30 and policy and charging rules function (PCRF)32. Details of these functions components are as follows.

Home agent or entity HA 18 provides media packet transfer in the homedomain or network 10 as Home Agent (hHA), and in the visited domain ornetwork 12 as Visited Home Agent (vHA). The HAs 18 map the homeaddresses with the temporary care-of-addresses, and route the media andsignaling messages to the mobile node 14.

SIP servers or entities, such as S-CSCF 26 and P-CSCF 22, take care ofrouting SIP signaling messages from and to the mobile node 14. S-CSCF 26is always located in the home network 10 and assists with user or MN 14registration regardless of the user location. In MMD network, either theP-CSCF 22 located in the home network 10 or the P-CSCF 22 in the visitednetwork 12 can be used for registration. Dynamic Host ConfigurationProtocol (DHCP) servers (not shown) in each network help assign theP-CSCF 22 address to the mobile node 14.

AAA 20 servers in both the home network 10 and visited network 12 areused for user profile verification. However, each of the visitednetworks 12 and the home network 10 can have different mobilitycapabilities and requirements depending on the verification policydefined by the individual network operators.

In addition, there are both SIP-based and non-SIP-based ASs 30 that areresponsible for providing advanced multimedia services beyond voice overinternet protocol (VoIP). PCRF 32 controls the media based on the policyin each home and/or visited network 10, 12, and helps to provide featureinteraction between SIP-based and non-SIP-based services. Depending onthe type of access network, e.g., CDMA, 802.11, etc., the architecturecan have AGWs 16 that may act as Gateway GPRS Support Node (GGSN),Packet Data Serving Node (PDSN) or Packet Data Interworking Function(PDIF).

Home local mobility is a scenario in which the mobile node 14 movesbetween two different access routers within a home domain 10. A similartype of movement in the visited domain 12 is called visited localmobility. Correspondingly, there can be several types of globalmobility. The first form of global mobility occurs when the mobile node14 moves from its home network 10 to the visited domain 12 of a newcarrier network. The second form of global mobility involves the mobilenode 14 moving from one visited domain 12 to another visited domain 12within the same carrier network. The third form of global mobilityhappens when the mobile node 14 moves from one carrier network toanother carrier network while away from the home domain 10.

Table 1 shows the possible combination of movement patterns that involvedifferent types of mobility support in the home domain 10 and in thevisited domain 12. The mobile node's stack can have either Simple IP orCMIPv6, and can move from the home domain 10 to the visited domain 12,where the home domain 10 and the visited domain 12 may offer differentmobility support. The grey areas are situations that are unlikely tohappen.

Mobility stack on mobile node Home Domain Visited Domain Simple IPv6Simple IPv6 Simple IPv6 PMIPv6 CMIPv6 PMIPv6 Simple IPv6 PMIPv6 CMIPv6CMIPv6 Simple IPv6 PMIPv6 CMIPv6 CMIPv6 Simple IPv6 Simple IPv6 PMIPv6CMIPv6 PMIPv6 Simple IPv6 PMIPv6 CMIPv6 CMIPv6 Simple IPv6 PMIPv6 CMIPv6

In order to reduce the load on the mobile node 14 and handle localmobility, the Internet Engineering Task Force (IETF) has been developingnetwork-based localized mobility management protocols. These protocolsare designed to take care of local mobility and are controlled by thenetwork elements in the access routers. One such protocol is PMIPv6,which does not use any mobility stack on the mobile node 14 but ratheruses functions or proxies on the access routers to help perform themobility functions, such as the binding update to the HA 18. Thesefunctions or functional components are called Mobile Access Gateway(MAG) and can co-locate with the access routers. As long as the mobilenode 14 moves within the same domain that has MAGs, the mobile node 14assumes that it is in a home link. The MAG is responsible for sendingthe proper mobile prefix as part of the router advertisement forstateless auto-configuration, or it can also act as a DHCP relay agentfor stateful auto-configuration.

FIG. 2 describes the network elements associated with PMIPv6 operation,and illustrates mobile node 14 handoff from visited network 1 12 tovisited network 2 12. The mobile node 14 is in communication with acorrespondent node (CN) 34. AGW1 16 and AGW2 16 each include a mobileproxy or MAG 38, and each has a tunnel 36 with HA 18.

After the mobile node 14 connects to the new point-of-attachment as partof the initial bootstrapping process or after the movement to a newdomain, access is authenticated with the designated AAA 20 server.During this process, MAG 38 sends the binding update to the HA 18 withthe address of the MAG 38 that is specific to the home prefix of themobile node 14. In the absence of a pre-existing tunnel, this processhelps to set up a tunnel 36 between the HA 18 and the respective MAG 38.The mobile node 14 configures its address using the prefix included inthe router advertisement and interface-id, which can be assigned by MAG38 or created by itself. The PMIPv6-based mobility protocol is preferredwhen mobility is confined within a domain and wireless service providersdo not want to overload the mobile node's stack by setting up a tunnel36 between the mobile node 14 and the HA 18. A tunnel is not desirableon the mobile node 14 because it adds extra processing and bandwidthconstraints to the wireless hop.

FIG. 3 illustrates roaming according to one embodiment of the invention.A home domain 10 includes entities or functional components of hP-CSCF22, hS-CSCF 26, hI-CSCF 24, hHA 18 and hDHCP 40. In addition, the homedomain 10 includes hPDSN routers each having a proxy mobile agent 38.The visited domain 12 includes entities of vP-CSCF 22, vS-CSCF 26,vI-CSCF 24, vHA 18 and vDHCP 40. The visited domain 12 also includesvPDSN routers, each having a mobile agent gateway 38. MN1 14 and MN2 14are in visited domain 12. A tunnel 36 is established between each MAG 38and hHA 18 in the home domain 10. Tunnels 36 are also created betweeneach MAG 38 and vHA 18 in the visited domain 12. During sessionenablement, when the end nodes are notified of the signaling address andSession Description Protocol (SDP) address, media and signalingsplitting is performed. The tunnels 36 carry the split traffic, so thatSIP signaling is transmitted over one tunnel, and media for SIP as wellas non-SIP application is sent over another tunnel. Each applicationspecific media uses different contact address for transport.

FIG. 4 shows the case of home local mobility when the mobile node 14 hasa Simple IP stack, and the home network 10 is equipped with PMIPv6.Generic network architecture having access routers that behave as 3GPP2PDSN are assumed, and a Local Mobility Anchor (LMA) serves as HA 18. Asthe mobile node 14 initially bootstraps in PDSN#1, it goes through anaccess authentication phase. With a Point-to-Point Protocol (PPP) link,access authentication takes place at the lower layer during the LinkControl Protocol (LCP) and authentication phase. Since the PDSNs areequipped with MAG 38, the Network Access Identifier (NAI) is passed tothe LMA 18 as part of the binding update, during which a tunnel 36 iscreated between MAG 38 and LMA 18. MAG 38 may also receive the homeprefix and the interface-id for the specific mobile node 14 from the LMA18. These are used for creating the hHoA#1 address.

The mobile node 14 interacts with the DHCP server to obtain the addressof the P-CSCF 22. It then sends a SIP registration to the P-CSCF 22, andthe P-CSCF 22 sends this registration to S-CSCF 26. Since hHoA#1 is usedfor the purpose of SIP signaling, the mobile node 14 uses the HoA'sprefix and locally generated random interface-id to generate the newmedia addresses, hHoA#2 and hHoA#3, for SIP-based and non-SIP-basedtraffic, respectively. The mobile node 14 uses hHoA#2 as the mediacontact address in its SDP when the mobile node 14 invites another useror correspondent node 34. Consequently, the mobile node 14 receivesmedia for the SIP-based application using a different IP address thanfor SIP signaling.

Since there is already a tunnel 36 established between the MAG 38 andLMA 18, any SIP signaling traffic destined for hHoA#1, SIP mediadestined for hHoA#2, and non-SIP media destined for hHoA#3 are tunneledvia the PMIPv6 tunnel 36 setup between the MAG 38 and LMA 18. In oneembodiment (not shown), separate tunnels are established for each of SIPsignaling traffic, SIP media and non-SIP media. In all cases, even ifthe mobile node 14 moves to a new PDSN#2, and hence changes to a new MAG38, hHoA#1, hHoA#2, and hHoA#3 do not change.

FIG. 5 shows the flows for the case in which the mobile node 14 has aSimple IP stack, and both the home domain 10 and visited domain 12support PMIPv6. As in FIG. 3, LMA serves as a form of HA 18. The firsttime the mobile node 14 moves to the visited domain 12, access isauthenticated along with the PMIPv6 binding update procedure with MAG38. During the access authentication, the MAG 38 sends two bindingupdate messages to two LMAs 18. One binding update message is sent tothe visited LMA 18 and the other is sent to the home LMA 18 according tothe authentication response message from the visited AAA 20 and home AAA20. MAG 38 sends the interface-id during the IPv6CP procedure, and sendsboth the vHoA's prefix and hHoA's prefix as part of the routeradvertisement message. Based upon these three parameters, the mobilenode 14 generates hHoA#1 used for SIP signaling, and vHoA#1 used formedia packets. The mobile node 14 then obtains the address of homeP-CSCF 22 from the home DHCP server through the PMIPv6 tunnel 36 betweenthe MAG 38 and home LMA 18, and sends SIP registration to the homeP-CSCF 22. The home P-CSCF 22 forwards it to home S-CSCF 26 to updatethe user information. After a successful SIP signaling setup, the mobilenode 14 receives traffic using the vHoA#1 address. In order to send thenon-SIP media packets, the mobile node 14 creates vHoA#2 using aself-generated interface-id and vHoA's prefix. During handoff, themobile node 14 obtains the same prefixes from the visited LMA 18 andhome LMA 18. Therefore, the mobile node 14 does not have to send an SIPregistration message unless the assigned P-CSCF 22 changes.

While the present invention has been described in particularembodiments, it should be appreciated that the present invention shouldnot be construed as limited by such embodiments, but rather construedaccording to the claims below.

1. A method for mobility support of a mobile node having a home networkin a heterogeneous roaming environment, said method comprising the stepsof: authenticating the mobile node in a visited network and obtaining anaddress for the mobile node in the visited network; establishing asecurity connection between a functional component in the visitednetwork and an agent in the home network; creating a home address forthe mobile node; and generating, using the home address, a SIP signalingaddress, a SIP media address, and a non-SIP media address; wherein SIPsignaling is transmitted using the security connection to the SIPsignaling address, SIP media is transmitted using the securityconnection to the SIP media address, and non-SIP media is transmittedusing the security connection to the non-SIP media address.
 2. Themethod according to claim 1, wherein the home address for the mobilenode is obtained from a functional component of an access router in thevisited network.
 3. The method according to claim 1, wherein thesecurity connection is established over a tunnel.
 4. The methodaccording to claim 1, wherein the functional component is a mobile proxyand the agent is a local mobility anchor.
 5. The method according toclaim 1, wherein the home address is created during SIP registration andthe home address comprises a prefix and an interface-id.
 6. A method formobility support of a mobile node having a home network in aheterogeneous roaming environment, said method comprising the steps of:authenticating the mobile node in a visited network and obtaining anaddress for the mobile node in the visited network; establishing morethan one security connection between a functional component in thevisited network and an agent in the home network; creating a homeaddress for the mobile node; and generating a SIP signaling address forSIP, a SIP media address for SIP media, and a non-SIP media address fornon-SIP media using the home address; wherein SIP signaling istransmitted using a first of the security connections to the SIP mediaaddress, SIP media is transmitted using a second of the securityconnections to the SIP media address and non-SIP media is transmittedusing a third of the security connections to the non-SIP media address.7. The method according to claim 6, wherein the home address for themobile node is obtained from a functional component of an access routerin the visited network in cooperation with the agent in the homenetwork.
 8. The method according to claim 6, wherein the securityconnection is established over a tunnel.
 9. The method according toclaim 6, wherein the functional component is a mobile proxy and theagent is a local mobility anchor.
 10. The method according to claim 6,wherein the home address is created during SIP registration and the homeaddress comprises a prefix and an interface-id.
 11. A system formobility support of a mobile node having a home network in aheterogeneous roaming environment, said system comprising: a visitednetwork authenticating the mobile node and determining an address forthe mobile node; a security connection between a functional component inthe visited network and an agent in the home network; a home address forthe mobile node; a SIP signaling address generated using the homeaddress; a SIP media address generated using the home address; and anon-SIP media address generated using the home address, wherein SIPsignaling is transmitted using the security connection to the SIPsignaling address, SIP media is transmitted using the securityconnection to the SIP media address, and non-SIP media is transmittedusing the security connection to the non-SIP media address.
 12. Thesystem according to claim 11, wherein the home address for the mobilenode is obtained from a functional component of an access router in thevisited network.
 13. The system according to claim 11, wherein thesecurity connection is a tunnel.
 14. The system according to claim 11,wherein the functional component is a mobile proxy and the agent is alocal mobility anchor.
 15. The system according to claim 11, wherein thehome address is created during SIP registration and the home addresscomprises a prefix and an interface-id.
 16. A system for mobilitysupport of a mobile node having a home network in a heterogeneousroaming environment, said system comprising: a visited networkauthenticating the mobile node and determining an address for the mobilenode; a plurality of security connections between a functional componentin the visited network and an agent in the home network; a home addressfor the mobile node; a SIP signaling address generated using the homeaddress; a SIP media address generated using the home address; and anon-SIP media address generated using the home address, wherein SIPsignaling is transmitted using a first of the plurality of securityconnections to the SIP signaling address, SIP media is transmitted usinga second of the plurality of security connections to the SIP mediaaddress, and non-SIP media is transmitted using a third of the pluralityof security connection to the non-SIP media address.
 17. The systemaccording to claim 16, wherein the home address for the mobile node isobtained from a functional component of an access router in the visitednetwork.
 18. The system according to claim 16, wherein the securityconnection is a tunnel.
 19. The system according to claim 16, whereinthe functional component is a mobile proxy and the agent is a localmobility anchor.
 20. The system according to claim 16, wherein the homeaddress is created during SIP registration and the home addresscomprises a prefix and an interface-id.